Just make sure that you buy from someone who is an authorized dealer for the brand of TV that you plan on buying. That way, you can return the TV to the dealer and you won't have to mess with the manufacturer - which is a good thing since they're almost always a major pain in the ass and slow as hell.
I've been looking into buying a plasma myself, and so far I really can't find a compelling reason to fork over the extra dough for an HD model, so I might just go ED instead. This Panasonic ED got the best ratings of any plasma that I could find:
http://www.newegg.com/app/ViewProductDesc.asp?description=24-187-012&depa=0
And the comparable Sony is also a pretty decent choice, although their build quality can be sketchy.
Also, consider the fact that many plasmas don't come with a built-in TV tuner, which will run you anywhere from a hundred to a few hundred extra dollars. And then you may also have to buy a stand or a wall mount, which will be an extra couple of hundred bucks.
From what I've heard, the lifespan of modern plasmas isn't really an issue anymore, with some models having a half-life* of around 60,000 hours. For the lazy people out there, that's roughly 33 years of viewing at around 5 hours/day.
Anyway, I'm interested to hear what some of the tech geeks here have to say about plasma technology. It has a few pitfalls, mainly the price - but once you see a nice one in action it's hard to think about buying a regular TV again.
*time for the plasma cells to deteriorate so that their peak intensity is half of what it was initially.
